The advent and development of Polymerase Chain Reaction (PCR) since 1983 has revolutionized molecular biology through vastly extending the capability to identify, manipulate, and reproduce DNA. A number of different applications have been developed to utilize PCR, such as scientific research, clinical diagnostics, forensic identifications, and environmental studies.
Following the sequencing of the human genome, genomic analysis of the estimated 30,000 human genes has been a major focus of basic and applied biochemical and pharmaceutical research. Diagnostics, medicines, and therapies for a variety of disorders may be developed from the analysis and manipulation of genes. Diagnostic devices often utilize small samples from patients. Patient samples collected for diagnostic purposes are typically of limited quantity and volume and thus only a small number of tests can be performed on a single sample. Therefore, there is need for a miniaturized device capable of performing analysis of a large number of genes or nucleic acid sequences from a single small sample.
Development of gene-based therapies has also become a major focus for both researchers and pharmaceuticals. In order to develop new therapies and recognize new therapeutic targets, high-throughput screening utilizing most, if not all, of an entire genome of an organism would be desirable. In addition, the ability to sequence and amplify an entire genome from a sample from an individual may pave the way for the development of personal medicines.
Many of the PCR microplates and thermocyclers currently available are unable to performing a large quantity of PCR at a reasonable cost. In many reactions, the sample volume needed to analyze each individual sequence is on the order of microliters. When sequencing or amplifying thousands of genes, the amount of sample needed from an individual or group of individuals often becomes not practical. In addition, when dealing with a large number of sequences, the sensitivity and specificity of the reactions become a major issue when performing PCR. The annealing temperatures necessary for PCR amplification of a sequence can vary by as much as 15° C. from sequence to sequence. In order to sequence thousands of genes from a relatively small sample, a thermal cycling apparatus needs to adapt to range of different temperatures.
In recent years, the advancement in nanofabrication technology enabled the production of miniaturized devices integrated with electrical, optical, chemical or mechanical elements. The technology embodies a range of fabrication techniques including low-pressure vapor deposition, photolithography, and etching. Based on these techniques, miniaturized devices containing silicon channels coupled to nano-heaters have been proposed (see, for example, U.S. Pat. Nos. 6,962,821, 6,054,263, 5,779,981 and 5,525,300). While the channel- or chamber-based design in principle reduces the thermal mass and the reaction volume, it still suffers from other practical drawbacks. In particular, the channels or chambers by design are limited with respect to controlling temperature and evaporation.
Such devices or systems would greatly aid in diagnostic testing, pharmaceutical development, and personal medicine. The present invention satisfies this need and provides related advantages as well.